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Stormwater and Your Water: How Your Landscaping Affects the Bay

Preserving the Chesapeake Bay affects even those of us living near the top of the Bay watershed as the eco-systems are intrinsically linked through our rivers and precipitation. In Alexandria, our runoff flows into the Bay. The Bay remains on the EPA’s “dirty waters” list for Virginia, alongside hundreds of others within the state. The Occoquan Reservoir, which provides 45% of Northern Virginia’s clean drinking water, is also on this list. Due to variations between the EPA and Virginia Tech’s Occoquan Watershed Monitoring Lab, the reservoir is listed only for aquatic life impairments, despite its high levels of phosphorous, turbidity, low dissolved oxygen, and the presence of copper sulfate and pharmaceuticals.

Stormwater is one of the major causes of pollution to the Bay. Any precipitation in an urban area that does not evaporate or soak into the ground, and instead pools and travels downhill, is called stormwater. Forests and wetlands slowly absorb rainfall naturally but with urban development, impermeable surfaces such as roads and parking lots now cover much of our landscape. These manmade surfaces cause water and pollutants such as pesticides, bacteria, and motor oil to flow at a higher velocity into local waterways, eroding stream banks and suffocating the aquatic habitat with the eroded material.

The Prince William Conservation Alliance estimates that changes to as small as 2% of the watershed area could affect the water quality of the Occoquan Reservoir. Northern Virginia is populated by almost 2.5 million people, with over 140,000 in Alexandria alone. Imagine if each home or business owner made an effort to reduce runoff. By learning to limit stormwater erosion, our drinking water would become cleaner and our local seafood safer. Moreover, anyone who might accidentally swallow a big gulp of water swimming in the Potomac at some point in the future should have an incentive to begin properly disposing paints and other chemicals!

There are many small things we can each do to prevent the pollution that is carried in stormwater including properly disposing of trash and fixing fluid leaks on our cars. When landscaping, do not blow grass clippings and leaves onto the street or into storm drains. Paul Wheaton’s article, “Organic Lawn Care for the Cheap and Lazy,” discusses how to have a lush lawn without using harmful fertilizers while preventing runoff. Be sure also to properly dispose of materials such as paint and antifreeze by taking them to Alexandria’s Solid Waste Division located at 133 South Quaker Lane, Alexandria, VA. Call (703) 751-5872 for questions about acceptable materials and hours of operation.

When building, whether residentially or commercially, be aware of zoning. Alexandria has one of the strictest stormwater regulations in the state, as it contains provisions from the Virginia Chesapeake Bay Preservation Act and the Virginia Stormwater Management Act. Construction and post-construction regulations for Alexandria can be found in Article XIII of the City Zoning Ordinance, available online at. Remember also that preserving undisturbed vegetative cover is more cost effective when developing land than having to construct new stormwater management practices.

If it is not possible to conserve this covering, be sure to implement pervious surfaces in the new design. Save money and slow stormwater runoff by not making driveways or parking lots larger than necessary. Increasing the tree canopy over paved surfaces will intercept some of the rainfall as trees and forests capture and store rainfall in the canopy, releasing water into the atmosphere through evapotranspiration.

Another creative solution is planting a greenroof which is a living, vegetative roofing alternative. Not only do these roofs reduce pollution and run-off, they also help insulate and reduce the maintenance needs of buildings. The materials which compose our city buildings are primarily shades of black and gray, which soak up the sun’s radiation and reflect it back as heat, making cities 7 degrees hotter than surrounding areas. By adding a greenroof to a one-story building, its cooling costs can be reduced between 20 and 30 percent. Commercial buildings can also consider rooftop gardens as a less intensive way to improve air quality and lessen the pollutants in our rain. For more information, see the “Green Roofs in Alexandria” article.

Residentially, rain barrels can limit stormwater on a smaller scale. Since these barrels collect rainwater, having one or two of these outside your home can limit the amount of runoff on your property. This water can then be reused to wash cars or water gardens, all while slowing runoff and the transmission of pollutants into the Bay.